It is well known that the fine dispersion of liquids or powders in the air, or in other medium or surface is often necessary. The fields of application can be divided into two main groups.
One of them includes the applications where the quantity of the product discharged on each occasion is not considerable (therapeutic, cosmetic, household applications etc). The aerosol products were developed just for this purpose. These products are filled into pressurized containers and by actuating a valve mechanism, they pass to the air through an atomizer system. The finely dispersed liquid drops (aerosol drops) are produced by the atomizing nozzle.
Though the size could be increased, containers liter volume are usually not produced.
In the other group of applications a considerable amount of product is to be used on each occasion, as acceptable result will be attained only this way. Such fields of application are for example the disinfection of buildings, fire fighting, etc. Sprayers or atomizers of continuous operation are used for this purpose.
One cf these solutions is described in the HU-PS 185 548. This device is an improvement of the apparatus described in the DE-PS 28 40 723, U.S. Pat. No. 1,399,490, U.S. Pat. No. 4,116,387 and U.S. Pat. No. 4,251,033 for the purpose of administering active ingredients for therapeutic or immunogenic treatment of animals kept in stable. The apparatus consists of a high capacity rotary atomizer and conical drop separators opening by way of shutter. These drop separators prevent the passage of drops greater than 5 micron into the air space.
The apparatus according to the U.S. Pat. No. 4,687,135 was developed for discharge into the air space with high energy. The propellant in the apparatus is brought about by the explosion-like burning of gas, and pulverized metal, metal-ceramic, wear- and heat-resistant electrically insulating or electrically conducting material are admitted into the nozzle. The pulverized substance flowing out of the nozzle heated to the vicinity of its melting point, precipitates with high energy on the treated surface, forming a layer on it. The apparatus functions periodically.
These apparatuses are capable to discharge theoretically unlimited amount of product, but in fact they slow, because increasing the quantity discharged in time unit is restricted by the atomizing system. The slowness is unfavourable especially in apparatuses used for fire fighting, e.g. in fire extinguishers.
There are instances, among which the underground fire is the most characteristic, when very large amount of product has to be dispersed nearly all at once into a very large space. With the currently known spraying systems this is impossible, or it can be realized only with apparatuses of unacceptable size.